The trend of decreasing of lubricant film thickness in tribological systems is one of the important features of current tribology stirred up by the quest for higher efficiency and energy saving. As a result, the influence of the surface micro geometry on the contact performance and machine component life increases steadily. This has led to a systematic effort to develop a theory that describes unifying mechanism governing the amplitude reduction of harmonic patterns in EHL contact known as amplitude attenuation principle [1–2]. This theory provides formulas that can serve as a simple tool to predict the deformed geometry inside the contact for arbitrary micro geometry when used in combination with a Fourier analysis. Therefore, it is possible to give a reasonable explanation of the basic phenomena involved in real rough surface EHL and mixed lubricated contacts.